PHOTO: KADOC-KU LEUVEN, © STUDIO CLAERHOUT

Initially best known for its avant-garde, 20-foot-tall aluminum sculpture, "Risen Christ," seen here, the Vatican pavilion at Expo '58 is now famous for hiding a remarkable secret. The building contained a discreet library to which the Russian émigré staffers – one of whom was Leo Tolstoy's grandnephew – steered 3,000 of the pavilion's Soviet visitors and slipped them the novel "Doctor Zhivago" by the Russian dissident Boris Pasternak. The Central Intelligence Agency had arranged for the subversive tome to be covertly distributed at the expo, proving sometimes the pen is indeed mightier than the sword.